1. Field of the Invention
The present invention relates to a display control apparatus. More particularly, the invention relates to a dynamic image display control apparatus applicable to the dynamic image display of a ferroelectric liquid crystal display device.
2. Related Background Art
Traditionally, as a display device for a personal computer (hereinafter referred to as PC) or a work station (hereinafter referred to as WS), a CRT (Cathode Ray Tube) has been used. In recent years, however, a liquid crystal display device of TN (Twisted nematic) structure or STN (Super Twisted nematic) structure has been in use for a lap top PC and others because of its lightness and thinness which are advantageously brought about by its structure.
Also, it is required for the display device for the PC or WS to expand a window function or other graphic functions in order to enhance the visual comprehension based on the human-factors engineering. To implement this, a high resolution and a large screen are needed.
However, when increasing the number of scanning lines for a higher resolution, the liquid crystal display devices of TN, STN, and the like need a liquid crystal material having acutely sensitive electrooptic characteristics to secure a margin required for the display contrast. On the other hand, a ferroelectric liquid crystal having bistability enables images to be displayed on a large screen with a high resolution. However, ferroelectric liquid crystals hitherto known are not fast enough to execute a highly minute display due to its temperature characteristics when operational temperatures are low.
When the speed of the ferroelectric liquid crystal display is not high enough, there is known a method of image representation using a high order interlacing (hereinafter referred to as multi-interlace) to prevent flickering. This multi-interlace representation, however, causes so-called "dispersion" in displaying a pointing device, pop-up menu, scroll, and the like when a dynamic image should be displayed; thus degrading the quality of display after all.
For the prevention of the "dispersion" in display, there is known a method for partially rewriting images by non-interlacing for an object to be represented at high speeds. The image display control in this respect has hitherto been conducted using the video memory provided in the host computer. Such a display control apparatus is structured by adding a display control adapter 601 to a mother board 602 of a host computer 603 as shown in FIG. 6. As a result, "dispersion" in display on ferroelectric liquid crystal display device 600 is avoided. Alternatively, a display control adapter 611 can be added to an expansion slot 612 of host computer 613 to achieve the same effect on ferroelectric liquid crystal display device 610, as shown in FIG. 7.